First you have to desolder the old LEDs. Be careful not to destroy the fine tracks on the PCB.

Lay your knife under the first LED and warm up one side of it so you can gently press this side of the LED away from the PCB (don't use too much force,or you'll break the pad completely off the PCB). Tip: It usually helps if you melt a tiny bit of new solder onto the pad when you start (the flux in the new solder will help the old solder on the pad to liquidize).

Then take your forceps to remove the LED after you warmed up the other side.

Take your soldering iron again to flatten the solder on the PCB pads. This is important if you want to place the new LED in a plane position. Tip: You can use a junk piece of electrical wire (not solid, single core, though) as solder wick to suck up the excess solder from the pad. Braided copper wire (often sold as "bell wire") works best for this.

Before you start please note the position of the plus pole of the old LEDs.
It is on the right side of them (if you have all three LEDs to your body - LAN and AC connection away from your body).
All LEDs have a small point, line or a cut edge at the side of the plus-pole.

You can also test the new LEDs before you solder them. Just take them with your forceps onto the newly clean connections for the LEDs.
Now you know in which direction you have to solder them (maybe you did before - but now you are sure).

Place the first LED carefully on the PCB in the middle of this little white frame printed on the PCB.

warm up your soldering iron and heat one side of the LED carefully (there are very small items near the LEDs - so be careful!)

at this time you can relocate the new LED, so it is in the right position

Now heat up the other side of the LED shortly. The tin on the pcb and some more tin on your soldering iron should be enough to fix it strongly.

That’s it. You have soldered your first new LED on your LaFonera. Repeat these three steps and you only have to clean up your workspace before you have finished your work.

If your soldering iron is too big for the very small SMD-LEDs you can attach a paperclip on it.
This gives you the possibility to work much more precisely with these small items. If you add some tin between the connection of soldering iron and paperclip the heat will be much better carried forward. Make sure to attach it strongly enough so that it won't get lost.
Maybe you have to test which paperclip works best for you, because they are made of some different materials.